1. Field
Methods of programming or erasing a nonvolatile memory device having a charge storage layer, for example, including performing at least one unit programming or erasing loop, each unit programming or erasing loop including applying a programming pulse, an erasing pulse, a time delay, a soft erase pulse, soft programming pulse and/or a verifying pulse as a positive or negative voltage to a portion (for example, a word line or a substrate) of the nonvolatile memory device.
2. Description of the Related Art
Non-volatile memory retains information stored in its memory cells even when no power is supplied. Examples include mask ROM, EPROM, and EEPROM.
Non-volatile memory is widely used in various kind of electronic products, for example, personal computers, personal digital assistants (PDAs), cellular phones, digital still cameras, digital video cameras, video game players, memory cards, and other electronic devices.
Memory cards types may include multimedia cards (MMC), secure digital (SD) cards, compact flash cards, memory sticks, smart media cards, and extreme digital (xD) picture cards.
Among non-volatile memory devices, a flash memory is widely used. Flash memory may be divided into a Not-OR (NOR) type and a Not-AND (NAND) type based on a connection structure of cells and bit lines. Because a read speed is faster and a write operation is slower, a NOR-type flash memory may be used as a code memory. Because a write speed is faster and a price per unit area is lower, a NAND-type flash memory may be used as a mass storage device.
NOR-type flash memory may be used in BIOS/networking in a PC, a router, or a hub or in a telecommunications switcher. NOR-type flash memory may also be used to store code or data for cellular phones, personal digital assistants (PDAs), POS, or PCA.
NAND-type flash memory may be used in memory cards for mobile computers, digital cameras, both still and moving, near-CD quality voice and audio recorders, rugged and reliable storage, for example, solid-state disks.
FIG. 1 illustrates a conventional program loop including a plurality of unit program loops using an ISPP method. As illustrated in FIG. 1, one unit program loop may include a program operation and a verify read operation. In the program operation, a program voltage Vpgm may be applied to a selected word line and a pass voltage Vpass may be applied to the unselected word lines. In the verify read operation, a verify voltage Vvfy may be applied to the selected word line and a read voltage Vread may be applied to the unselected word lines. In conventional ISPP fashion, the program voltage Vpgm may be increased by a delta voltage ΛV for each unit program loop.
Similarly, FIG. 2 illustrates a conventional erase loop including a plurality of unit erase loops using an ISPP method. An erase loop may include an erase operation and a verify read operation. The erase operation may include the application of an erase voltage Vers to the substrate of a selected block. The verify read operation may include the application of a verify voltage Vvfy to the selected word line and a read voltage Vread to the unselected word lines. In conventional ISPP fashion, the erase voltage Vers may increase by a delta voltage ΛV for each unit erase loop.